• Atmosphere
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• v.19 no.1
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• pp.67-78
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• 2009

A strong negative correlation has been detected between the North Pacific Oscillation Index (NPI) and the Effective Drought Index (EDI) in May over Korea. In May of positive NPI year, anomalous patterns caused a drought in Korea as follows: the anomalous south-low, north-high low-level pressure patterns in the northeast and southeast of Korea have strengthened the anomalous northerlies to Korea. In addition, these anomalous northerlies have prevented western North Pacific (WNP) high from moving northward. As a result, anomalous descending flows have strengthened in the mid-latitude region in East Asia. In the WNP, the anomalous south-high, north-low sea surface temperature (SST) has been widely distributed, which has strengthened anomalous south-low, north-high low-level pressure patterns. These anomalous characteristics of pressure and SST patterns observed in May of positive NPI years have already been detected in previous winter (December-February) and early spring (March, April). In addition, the anomalous negative sea ice concentration in the North Pacific during two seasons has strengthened the anomalous anticyclonic circulation in the same region and in turn made a contribution to formation of anomalous south-low, north-high pressure patterns in May.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.3
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• pp.13-24
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• 2013

Agriculture is affected directly by climate conditions and changes, and it is necessary to understand the impact of climate change on agricultural reservoirs which are the main water resources for paddy fields in Korea. This study aimed to evaluate the impact of climate change on the anti-drought capacity including water supply capability (WSC) and drought response ability (DRA) of agricultural reservoirs based on RCP (Representative Concentration Pathway) 4.5 and 8.5 scenarios of CanESM2 (The Second Generation Earth System Model) provided by CCCma (Canadian Center for Climate Modeling and Analysis). The WSC and DRA were estimated using frequency analysis and runs theory. The six reservoirs (Yooshin, Nogok, Kumsung, Songgok, Gapyung, Seoma) were selected considering geographical characteristics and design criteria of reservoir capacity. In case of Seoma reservoir, more than 10 year drought return period (DRP), the variation of the WSC was estimated larger than the others. In case of Yooshin reservior (2~5 DRP) DRC was decreased in 2025s under RCP8.5. These results could be utilized for agricultural reservoirs management and future design criteria considering climate change impacts on paddy irrigation.

• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.3
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• pp.1-13
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• 2018

Recently, the frequency and intensity of drought have been increasing due to the sudden abnormal climate in Korea. The occurrence of agricultural drought has been steadily increasing from 5 times in the 1980s to 2000s in 20 years, 6 times in the 10 years from 2000 to 2010, and 4 times in the recent period from 2011 to 2015. Therefore, this study analyzed the effect of water shortage caused by drought by improving the function of agricultural reservoir. The target area analyzed the data such as "Comprehensive Information System for Rural Water" operated by Korea Rural Community Corporation. As a result, we selected the target area as Wanju - gun, Jeollabuk - do in consideration of the rate of water storage compared with the normal 25 years, the completion year of the facility, the area of coverage per reservoir site and the low capacity. As a result of evaluating the improvement effect of agricultural facilities, it was analyzed that the irrigation area increased by about 25.7% when the water level was increased by 1m and the irrigation area increased by about 51.3% when the water level was increased by 2m. The results of the drought impact assessment after improving the function of the agricultural facilities were analyzed that it was effective to improve the function after more than 4m depth.

• Journal of the Korean earth science society
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• v.43 no.1
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• pp.110-118
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• 2022

Frequent drought damage has resulted in the polarization of water resources. In Korea, local periodic abnormal droughts continued to occur between 2011 and 2017, resulting in decreased water storage rates of small-scale reservoirs designed with a frequency of 10-year droughts. This decrease can degrade water quality and limit the use of already secured quantities. Therefore, to prepare for and overcome drought, quality management and recalculation of drought frequency are required. This study estimates the potential pollutants causing quality changes in the reservoir. In addition, it reviews the decrease in storage and consequent changes in the quality of a reservoir during drought.

• Journal of The Korean Society of Agricultural Engineers
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• v.66 no.5
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• pp.29-40
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• 2024

Most agricultural reservoirs were built between the 1940s and 1970s. Therefore, it is necessary to evaluate the current water supply safety, considering changes in water capacity, the water management, and environment in relation to the passage of time.. The design frequency of drought, the number of years areservoir needs to be able to withstand a drought phenomenon, foragricultural water resources in Korea is the 10-year drought. As the water supply system and water supply patterns change, it is necessary to establish a concept of water supply reliability, which refers to the stability of water supply. This study evaluated the water supply reliability of agricultural reservoirs based on the designed frequency. The previously designed frequency and water balance analysis were used to calculate and analyze reservoir storage capacity, water supply turnover, water supply amount, water supply potential, water utilization safety, and water supply reliability. As a result, Yongmyeon Reservoir was found to be stable in terms of water supply reliability, whereas Seongho and Yongpung Reservoirs were found to be unstable using all methods. In particular, when converting the water utilization safety and the water supply reliability to the frequency of drought, Seongho and Yongpung Reservoir were in the lowest class, with a frequency of drought less than four years. Thus, we recommend that the consideration of water supply reliability be included in the preparation of adaptive measures and water supply strategies as changes in environmental conditions continue to develop.

• Journal of Korea Water Resources Association
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• v.45 no.5
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• pp.481-493
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• 2012

The Uncertainty of drought events can be regarded as supernatural phenomena so that the uncertainty of water supply system will be also uncontrollable. Decision making for water supply system operation must be dealt with in consideration of hydrologic uncertainty conditions. When ultimate small quantity of precipitation or streamflow lasts, water supply system might be impacted as well as stream pollution, aqua- ecosystem degradation, reservoir dry-up and river aesthetic waste etc. In case of being incapable of supplying water owing to continuation of severe drought, it can make the damage very serious beyond our prediction. This study analyzes comprehensively sustained drought impacts on the Han River Basin Water Supply System. Drought scenarios consisted of several sustained times and return periods for 5 sub-watersheds are generated using a stochastic hydrologic time series model. The developed drought scenarios are applied to assess water supply performance at the Paldang Dam. The results show that multi-year drought events reflecting spatial hydrologic diversity need to be examined in order to recognize variation of the unexpected drought impacts.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.3
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• pp.119-131
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• 2010

Drought is one of disaster causing factors to produce severe damage in the World because drought is destroyed to the ecosystem as well as to make difficult the economy of the drought area. This study, using Palmer Drought Severity Index carries out correlation analysis with sea surface temperatures. Comparative analysis carries out by calculated Palmer Drought Severity Index and past drought occurrence year. Result of comparative analysis, PDSI indexes were in accord with the past drought. Cluster analysis for correlation analysis carries out using precipitation and temperature that is input datas palmer drought severity index, and the result of cluster analysis was classified as 6. Also, principal component carries out using result of cluster analysis. 14 principal component analyze out through principal component analysis. Using analyzed 14 principal component carries out correlation analysis with sea surface temperature that is delay time from 0month until 11month. Correlation analysis carries out sea surface temperatures and calculated cycle component of the low frequency through Wavelet Transform analysis form principal component. Result of correlation analysis, yang(+) correlation is bigger than yin(-) correlation. It is possible to check similar correlation statistically the area of sea surface temperature with sea surface temperature in the Pacific. Forecasting possibility of the future drought make propose using sea surface temperature.

• Journal of Korea Water Resources Association
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• v.52 no.8
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• pp.545-554
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• 2019

The most drought assessments are based on a drought index, which depends on univariate variables such as precipitation and soil moisture. However, there is a limitation in representing the drought conditions with single variables due to their complexity. It has been acknowledged that a multivariate drought index can more effectively describe the complex drought state. In this context, this study propose a Copula-based drought index that can jointly consider precipitation and soil moisture. Unlike precipitation data, long-term soil moisture data is not readily available so that this study utilized a Gaussian Mixture Non-Homogeneous Hidden Markov chain Model (GM-NHMM) model to simulate the soil moisture using the observed precipitation and temperature ranging from 1973 to 2014. The GM-NHMM model showed a better performance in terms of reproducing key statistics of soil moisture, compared to a multiple regression model. Finally, a bivariate frequency analysis was performed for the drought duration and severity, and it was confirmed that the recent droughts over Jeollabuk-do in 2015 have a 20-year return period.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.4
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• pp.1117-1123
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• 2014

Water is a necessary condition of plants, animals and human. The state of the water shortage, that drought is globally one of the most feared disasters. This study was calculated target standardized precipitation index with unit of region for judgment and preparation of drought in consideration of the regional characteristics. First of all, Standardized Precipitation Index (3) were calculated by monthly rainfall data from rainfall data more than 30 years of 88 stations. Parametric frequency and nonparametric frequency using boundary kernel density function were analysed using annual minimum data that were extracted from calculated SPI (3). Also, Target return period sets up 30 year and target SPI analysed unit of region using thiessen by result of nonparametric frequency. Analyzed result, Drought was entirely different from severity and frequency by region. This study results will contribute to a national water resources plan and disaster prevention measures with data foundation for judgment and preparation of drought in korea.

• Journal of Climate Change Research
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• v.6 no.3
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• pp.223-231
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• 2015

Although a considerable part of climate change can be explained by temperature change, hydrological change such as precipitation, evapotranspiration, and runoff impact more on society. For the ascertain a hydrological change in agriculture sector, this study estimate evapotranspiration of cropland in the Korean peninsula, and then to assess the drought severity in the past 30 years through the estimated potential evapotranspiration and observed precipitation. The potential evapotranspiration is estimated by EPIC model and Penman-Monteith method and the drought severity in cropland of the Korean peninsula is assessed using Normalized Precipitation Evapotranspiration Index (NPEI) based on the difference in precipitation and potential evapotranspiration. In North Korea, the estimated evapotranspiration tends to increase even though a significant change is not found due to the change of climate. Although a time series change in drought severity in the past 30 years is not pronounced, a deviation by year and difference between South and North Korea is certain. One reason of this is difference in precipitation and evapotranspiration change according to the latitude. The result including expansion of facilities for water management in North Korea can be used for agricultural decision making, as well as base data of climate change adaptation.